Define food science
Food science could be a discipline within the biological, physics & engineering are wont to study the character of foods, the reason behind their deterioration, & the principles underlying food processing.
The relation of food science with other branches of science.
Food science may be a systematic study of the character of food materials & the scientific principles underlying their modification, preservation & spoilage.
To understand food science the essential concept of physics, chemistry, mathematics, & biology & their applications i.e biochemistry, microbiology & food technology is important to organize, store, & serve wholesome & high-quality products.
All food is chemical compounds that undergo various chemical reactions in any respect stages from production to consumption. These reactions have supported the law of chemistry. Many processes used while preparing food involved physical changes except for chemical changes.
Mater exists in 3 states – solid, liquid & gas. With the increased temperature a pure substance will change from solid to liquid & then to gas.
Many organic compounds will decompose undergoing various chemical reactions.
Many foods are a fancy mixture of chemical substances. In processed food additives are added to enhance color, texture, flavor, etc & these additives also are chemical compounds.
The objectives of the discipline are to develop a basic scientific understanding of food processing as determining through biochemistry, chemistry, physics,& other science. Food science & technology is that the key to the conversion of raw agricultural material into a wild sort of properly processed & preserved food, thus contributing to the well-being, economy, standard of living& progress of humanity. it’s a groundwork & applies principal & practice from a broad spectrum of basic & technology including:
• Biology – botany, bacteriology, microbiology, mycology.
• Chemistry – biochemistry, physical, analytical,&organic chemistry. • Physics – rheology, thermodynamics, cryogenic, radiophysics, ultrasonic • Nutrition & psychology – sensory behavior.
• Medicine – metabolism, toxicology, health & diseases.
Different scopes of the topic
1. Food analyst & chemistry –Investigation of the fundamental components of food which will be physical, organic & biochemical properties. The changes that occur during preparation involve texture, color, flavor & also associated with the nutritive value of food.
2. Food quality factors & their measurement – they cover the area: appearance, texture, flavor, nutritional, sanitary, organoleptic changes, taste panels, etc.
3. Nutritive aspects of food constituents & the effect of processing & handling – the nutritive value will be increased during handling, processing, or storage. During fermentation, removal of moisture or adding additives, etc the nutrients may be enriched. this information helps in regulating the nutritional value of the food supply.
4. Food microbiology, mycology & toxicology – Use of yeast, mold, bacteria in food production is important. Microbiological culture, monitoring, sampling & testing methods are essential. Identification of toxicity & stop the spoilage of food is required.
5. Food processing & engineering – Food processing plants, food packaging materials, methods, testing & evaluation effect on the period of food. Energy conservation & internal control is extremely important within the food sector.
6. nutrient development – food development is commonly commodity-related. These sorts of products have to be dispensed within the pilot plant. Knowledge of food science &technology & the evaluation of their quality & marketability is required.
7. Food safety & regulation – Food sanitation is expounded to public health. Knowledge of food labeling. nutritional labeling, food laws, food additives, food-born diseases, detection, identification, government & non-government agencies associated with food safety & current issues is important.
8. The food industry – Publication of major trade associations, industry standards, the structure of food industries, international food corporations, information of allied industries i.e.- packaging, chemicals, equipment knowledge is required.
Emerging Trends within the area of food science/ technology
Increased concern about nutritional content is extremely focused in those days.
Refined food is expressed by both consumers & nutritionists. Dietary guidelines & nutrition education target replacing refined food with whole grains, legumes & other food. Concern about food issues of safety is incredibly strong. Food scientists are responding to those nutritional & safety concerns in several ways, including increased attention to food interaction &bioavailability of nutrients, improved analytic & detection methods & research & education in food safety. New product developments, new processing technology, are bringing the new area to food industries. Food biotechnology could be a growing area i.e. genetically modified food.
Principles of food sciences include food microbiology & food safety are vital within the food industry.
Classification -1. nature – plant & animal…..
(From 1st sem) 2. on structure – fibrous Example –in muscle myosin & globular
Protein example – globulin, albumin, etc
- on characterization – simple, conjugated &derived protein….
- on function – class I, class II, incomplete protein ……..
Native protein –
Protein found in leaving tissues of animals & plants is called native protein…..
Denatured protein –
It is a non-proteolytic modification in the original structure of the native protein. It gives rise to physical, chemical & biological properties. It is brought about by denaturing agents, increasing in temperature, extensive beating.
Three stages of denaturation –
1st stage structural alteration
2nd stage coagulation
3rd stage curdling
Effect of denaturation –
- react with proteolytic enzymes
- decreased solubility
- lose their biological activity as the enzyme is destroyed i.e browning reaction does not take place in boiled potato
- improved the flavor & texture
- It is irreversible unless it occurs in a very mild condition.
Factors affecting denaturation –
- surface denaturation
partially denatured protein prepared from collagen, an intercellular cementing substance of the cell, gelatin gel is affected by the following:
- concentration of gelatin
- fruits & vegetables
- whipping, sponges,& cream
It is a solution of sugar lactose, & water-soluble vitamins & minerals
It is a colloidal dispersion of protein & an emulsion of fat in water.
Water accounts for 87% of milk.
2 type of protein
- Casein- alpha,beta casine
- serum or whey protein – albumin,globulin
There are colloidal dimensions & make milk opaque. Casein is colloidally dispersed in milk as calcium phosphonate.
Fresh milk has a pH of 6.6& casein micelles are dispersed as a colloidal sol. When acid is added to milk casein micelles become stable & it coagulates, forming a gel.
calcium phosphonate+ H+ (acid) -> neutral casein + Ca++
Egg white is a viscous sol with proteins dispersed in it. It can be beaten into foam. The protein ovomucin, ovoglobulin, & conalbumin are necessary to form affine foam with small air cells. As air is incorporated into the liquid the water layer of egg white gets thinner. Surface denaturation takes place. It helps to make the foam rigid,& when heat is applied the protein coagulate forming a permanent foam.
- bubbles form on the surface, but all egg white is not broken up.
- foam is extremely unstable
- air cells are generally large
- the mixture is still fluid
- acid, salt vanilla are added at this stage
- Soft peaks
- air cells are medium-fine, all egg white exist as foam
- foam is fairly stable, slightly drainage occurs on short standing
- the mixture is shiny, flows easily in a bowl, but is elastic
- soft peak fall over to near the base of foam as the beater is lifted from foam
- sugar is added gradually at this age
- Stiff peaks
- air cells are fine, especially if acid is added at the foamy stage. The mixture is white & opaque.
- foam quite stable, some drainage occurs on prolonged standing
- the mixture is shiny, flows slowly in a bowl, but is still elastic
- peaks are still quite soft, but the tip of the peak falls over as the beater is pulled from foam
- egg white for soufflés& omelets are beaten to this stage
- egg white & sugar are beaten to this stage for some cakes & pie.
- air cells are very fine, the mixture is extremely white
- foam is not stable, drainage is rapid on long-standing
- the mixture is dull, has lost its ability to flow in the bowl mass is brittle & inelastic, peaks remain rigid points this stage is avoided for products of fresh egg white.
Once the beaten egg is reached its desired stage it should be used promptly otherwise it will stiffen upon standing without additional beating.
When the egg white is beaten beyond the stiff peak stage dry stiff foam, curdled in appearance, is obtained.
Over beating makes the surface a denatured film that is insoluble.
Egg yolk should be beaten extensively to forms a fine, fairly stable foam.
The foam is not denatured by beating, unlike egg white.
Factors affecting egg white foam formation
- Utensils should be large enough to allow for a full increase in the volume of foam. However, it should not be too large that the beater has no content with egg white.
- A fine wiper should be used to give fine small air cells.
- Egg white wipes readily at room temperature.
- The presence of fat, even in the trace, interferes with foaming &produces foam for less volume. Egg white should separate from egg white.
- Salt & cream of tartar is used in egg white foams. Both these ingredients delay foam formation.
- Addition of water up to 40% of the volume of egg increase the volume of foam. It also makes the product more trend’, especially in omelets &sponge cakes. It is incorporated towards the end.
- Sugar act as a hydrating agent & excess beating is required to produce a foam.
Fats & oils
Spoilage of fat is known as rancidity.
There are 2 types of rancidity hydrolytic rancidity – reaction with moisture.
- oxidative rancidity – reaction with oxygen
Auto oxidation – it is also a part of oxidative rancidity with 3 steps initiation, propagation, termination.
Prevention of rancidity.
Reversion – many fats & oils change flavor before becoming rancid. This change is very different from rancid flavor is called reversion.
Difference between rancidity &reversion
Rancidity may hydrolytic or oxidative with typical flavor change of rancid oil but for reversion, it is an onset of rancidity.
All oil turn rancid but for rent
All oil turns rancid but for rancidity some oil reverts…..
In rancidity, the smell is the same for all oils but reversion, there are specific smells….
- Ring structures
- Three-dimensional structures
Reducing sugar – They are sugars that possess free aldehyde Or ketone groups. All monosaccharides are reducing sugars.
Non-reducing sugar – Monosaccharides are linked together through their aldehyde or ketone groups & these groups are not free, the sugar is called non reducing sugar. Sucrose is anon- reducing sugar
Starch – Polysaccharides made with amylase & amylopectin……(picture of starch granules)
Effect of cooking on starch
Moist heat change is called gelatinization.
Factors affecting the gelatinization
- mixing & stirring
- concentration of starch
- duration of heat
- Type of starch
- Added ingredients
– sugar/acid/fats/milk protein
Retrogradation – amylase starch is less stable it leaves the water after cooling this is known as retrogradation.
Dry heat change in carbohydrates is called dextrinization.